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Old 10-24-2003, 01:37 PM   #1
kmleon
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Registered: Sep 2003
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Large emails (pop) won't finish download over satellite.


I have had this issue for a long time (2+ years) with Linux and large emails and satellite connection.
I normally use Kmail these days, but I've verified the same issues with Mozilla Mail and Evolution. I have had this problem under every version of Linux I've tried recently: Redhat (7.3/8.0/9.0), Debian, SuSE 8.2.
I do not have this problem under Windoze or OpenBSD, on the exact same system.
I've been using Linux since 1994.
I am on a satellite connection with anywhere from 400-1800Kbps downstream and 32-65Kbps upstream. Latency is an average 700-900ms.
Whenever I get an email over a few hundred KB in size, I can't ever get it to finish downloading.
It will show the progress of around 1-60Kb, but then it just sits there and never downloads.
I CAN download it if I reboot my computer into Windoze or OpenBSD and download it with Outlook from Windoze.
I have tried turning off my iptables rules to all ACCEPT, and still no difference.
I don't even know where to begin to look to track this really annoying issue.
Do I need to recompile some network setting in the kernel? Is there an equivalent setting to /etc/sysctrl.conf (openbsd) that maybe needs to be changed from the default in Linux?
Right now my current setup is SuSE 8.2 using Kmail (with all the updates as of10-24-03).
There is currently a 400 KB file I want downloaded into Linux. I could clear the mail manually at my mail server (which I control remotely), or download it into windows and copy it over to Linux, as I've done in the past. But I would rather have this issues FIXED.
Does anyone have any suggestions on what I can try to track this down?
The mail server and local system logs don't show anything useful, just the normal conenction handshake and it just sits there.
Any suggestions are appreciated.
Thanks.
 
Old 10-27-2003, 12:34 PM   #2
unSpawn
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Does anyone have any suggestions on what I can try to track this down? The mail server and local system logs don't show anything useful, just the normal conenction handshake and it just sits there.

Interesting. Does degrading only occur when talking to your SMTP server? What does a ping and traceroute test comparison show for those platforms? Does your firewall do any TOS or QOS munging on any of the platforms? Can you compare a firewall log for all of the platforms wrt a SMTP "conversation"? If you extract network settings from windows registry and compare them with OBSD and Linux (MTU, send/recv window settings, any scaling), can you see any tweakable differences? If it doesn't then you'll have to resort to using tcpdump or ethereal to compare "conversation" differences. If that won't show anything usefull you'll have to go down one level and check card-specific initialisation lines, card diagnostics (like MII), resource sharing, or just plain wonky HW driver behaviour under Linux...

BTW, Linux sysctl settings can be extracted from /proc running "sysctl -a". As root, running "sysctl -a | grep ^net" should get you all relevant network vars. For applying settings look for the /etc/sysctl.conf file which you can "sysctl -e -p /etc/sysctl.conf", else you'll have to echo the statements into /proc/net.
 
Old 10-28-2003, 06:14 PM   #3
kmleon
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Previously posted by unSpawn

Quote:
Interesting. Does degrading only occur when talking to your SMTP server?
Any POP3 server only. I have not trouble SENDING the large emails (even to myself for testing), just when I try to download it via POP. I haven't tried other protocol/services for this issue though. I have about a dozen accounts through about as many different servers/companies/providers, but I focused on the server I have control of. It only seems to happen with larger emails.

Quote:
What does a ping and traceroute test comparison show for those platforms?
No noticeable difference. The service works with both proxy on or off, though faster with proxy on for http (Ex: http://192.168.0.1:83 for browser settings). Doing tests on dslreports.com, pcpitstop, ruralnetworks and other sites all give roughly similar performance reports of the overall network around 400-1800 Kbps downstream and 32-60 Kbps upstream, and an average latency from 700-900 ms, though there are bad days in the thousands of milliseconds of course. But I'm only focusing on when the satellite system "seems" to be running fine but the email downloads still hang while everything else works.

Quote:
Does your firewall do any TOS or QOS munging on any of the platforms?
Let me be clearer about the setup:
satellite--[coax]--tx/rx sat box--[usb cable]--w2kpro laptop--3com pc-card nic---[ethernet]---hub---ethernet----my system

My system varies, I've tried under Windows w2k, Xp Home <gack>, XP Pro, OpenBSD 3.3, SuSE 8.2, Redhat 7.3/8.0/9.0, Debian (forget which version it was).
All the windows and OpenBSD systems can get email without this problem.
All the Linux systems have this problem.
I've tried it on 3 different laptops (not the router, but "my system") and two desktops with the same results.
I've setup two different systems as the firewall/router/nat previously it was an older generic laptop, now it's on an IBM thinkpad. I don't know if Norton Firewall has such capabilities or means of gleaning information.Both setups I've run w2k with all updates, since the satellite software is only "officially" supported under w2kpro,and the provider wouldn't give any support if I changed it to Linux (Assuming the USB/Networking drivers and encryption keys could even be setup to work with such a setup (I wish)).
It really seems to be something with Linux itself on the client system, but I'm still at a loss where to begin, so that's why I keep experimenting with swapping things out as I have. Still to no avail.
I've tried with just a cross-over cable to bypass any possible funkiness with the hub. I've done this over wireless, but stripped down to ethernet to avoid the possibility of any issues there.


Quote:
Can you compare a firewall log for all of the platforms wrt a SMTP "conversation"?
Just to reiterate, it's POP3 (downloading) not SMTP (sending/uploading) that I'm having trouble with. Since the "firewall" nat/router is w2k pro, and I've tried it with both the firewall on and completely turned off (software norton firewall on the w2k laptop that's connected to the satellite through usb, and to the network through it's pc card (which I've tried swapping out before)), I'm not sure how to extract that, nor if that is relevant?


Quote:
If you extract network settings from windows registry and compare them with OBSD and Linux (MTU, send/recv window settings, any scaling), can you see any tweakable differences?
Haven't gone that deep. I'm sure there will be significant differences having tweaked Solaris and Linux in the past and those were quite different, I shudder to think on the 'doze box.
I could look into that, though if you could kind of give me more specific steps to save me having to "google" for each, I'd appreciate it, otherwise I'll do what I can.

Quote:
If it doesn't then you'll have to resort to using tcpdump or ethereal to compare "conversation" differences.
I tried that in an informal way, but I'll try a more concerted effort and see what I can find.

Quote:
If that won't show anything usefull you'll have to go down one level and check card-specific initialisation lines, card diagnostics (like MII), resource sharing, or just plain wonky HW driver behaviour under Linux...
I don't know how this will help since it's on a wide range of hardware, laptops, desktops.
If you really think I should itemize and detail all this still, please verify and I'll do it. I really want this issue to stop.
Overview of client email system:
Vaio pcg-grt170 laptop (built-in NIC and built-in wireless card)
Vaio pcg-gr390 laptop (built-in NIC and orinoco gold wireless card)
"Generic" 1ghz laptop (built-in NIC and cisco wireless card)
Custom built tower desktop dual intel 866 cpu system with asus MB & onboard NIC.
Custom built tower desktop with AMD athlon 750 with asus MB and onboard NIC

Quote:
BTW, Linux sysctl settings can be extracted from /proc running "sysctl -a". As root, running "sysctl -a | grep ^net" should get you all relevant network vars. For applying settings look for the /etc/sysctl.conf file which you can "sysctl -e -p /etc/sysctl.conf", else you'll have to echo the statements into /proc/net. [/B]
I hope my responses help with more suggestions.
Thanks, for the useful information you have given so far, I 'll use in trying to track it down further.

Last edited by kmleon; 10-28-2003 at 06:26 PM.
 
  


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